Many commercial and industrial applications require motion control. Examples include 1) a valve or gate may need to be opened or closed at specific times and/or at specific rates; 2) a rotating mechanism, such as a sprinkler for irrigation purposes, may need to turn at a controlled rate or distribute water in a particular manner; or, 3) a turnstile which is pushed by a person may need to have its motion controlled in some fashion to, for example, ensure safety. Controlling the motion of any mechanism, such as a sprinkler or a turnstile, generally requires a source of energy. Often, a source of electrical energy is located in proximity to the movable mechanism. However, it is not always practical to provide electrical power from an external source to a motion control system. This may be because the movable mechanism is portable and wiring is cumbersome or because no electrical energy is available at the site of the movable mechanism. Additionally, there are costs associated with wiring electrical power to the site of a movable mechanism.
The present invention is directed toward a motion control apparatus employed in situations where there is no convenient nearby source of electrical energy. In the case of a rotating sprinkler, for example, the energy source which actually moves the rotating sprinkler mechanism is generally in the form of pressurized flowing water and electrical power may not be convenient or easy to obtain at the site of a sprinkler. Another movable mechanism at which electrical energy may not be convenient or easy to obtain is a human-powered turnstile, which is pushed by a person in order to gain access. In both these examples, it is possible to harvest energy from the source of energy which actually moves the mechanism, and this harvested energy can thus be used to power the electronic circuitry used for motion control. A sprinkler's rate of rotation may be controlled by electronic circuitry and the speed at which a turnstile turns to allow a person to safely pass through it may be controlled by electronic circuitry. The present invention utilizes the same energy source which provides power to move a mechanism to also provide power to electronic circuitry which accomplishes motion control.
U.S. Pat. No. 6,864,591 is entitled “Sprinkler Activated Generator,” discloses an apparatus for irrigation, such as a sprinkler, which includes an electric generator for generating electricity. Current sprinkler system designs use some method of dissipating energy to slow the rotation of the sprinkler in order to reduce or eliminate the so-called rooster tail effect of high rotation speeds. This rooster tail effect causes small and uneven distribution patterns. The '591 patent, amongst other things, discusses how the inclusion of an electric generator in a sprinkler may reduce this rooster tail effect. The present invention improves upon the '591 patent by using the electricity which is generated by the electrical generator to power electronic circuitry used to control the motion of the sprinkler.
It is, therefore, advantageous to harvest electrical energy from the kinetic energy of a moving mechanism, and to use that harvested energy to power electronic circuitry which provides motion control.